It's no insult to call Apple's new Mac OS X Snow Leopard the company's least exciting operating-system update in years.

Even Apple has been playing down the changes in Snow Leopard, calling them "enhancements and refinements" and asking only $29 for the update (it's free on new Macs). But after seeing OS X evolve so rapidly over the past eight years, buyers walking into Apple's stores may expect something dramatic from this update.

If so, they're bound for disappointment. The most important features in Snow Leopard (also known as Mac OS X 10.6) hide within it, waiting for programmers to craft new software to exploit them. On its surface, it offers mainly incremental adjustments, some in places that most home users won't look.

The faster performance that Apple touts should be the most obvious upgrade, but it remained somewhat elusive after Snow Leopard was installed on three Macs. A Mac mini shipped this spring and a roughly three-year-old iMac did not start up or shut down significantly faster after upgrades to the new software, while a new MacBook Pro laptop came closer to Apple's advertised improvements. Each needed a second or so less to copy a folder of about 750 MP3 files, 7 gigabytes' worth, in the new operating system.

None of these improvements adds up to a "Wow, this is so much snappier!" speed-up that everybody would notice without the help of a side-by-side comparison.

These computers had slightly less memory available for use by other programs. They did win back 6 or 7 gigabytes of disk space, which is nothing to dismiss -- but most users are far more likely to run out of memory than disk space.

Snow Leopard doesn't look or act that much different from Leopard, either, aside from some tweaks to the Dock, the strip of shortcuts on the edge of the screen. You can now get a preview of an application's open windows by clicking and holding on its Dock icon. And the Dock's Applications, Documents and Downloads folders provide a grid listing of their contents that's much easier to navigate than the one in Leopard.

Regular video viewers, and would-be video editors, will probably appreciate Snow Leopard's re-written QuickTime program, which can now trim, save and convert video files and record either your activity onscreen or the view through a Mac's built-in webcam.

Some office users, in turn, will get a major benefit from Snow Leopard: It can synchronize e-mail, contacts and calendars with those hosted on Microsoft's widely used Exchange Server 2007.

Finding Snow Leopard's smaller fixes can require some attention to detail. A click on the System Preferences window's Date & Time icon leads you to an option to have Snow Leopard set your location and time zone from nearby WiFi signals. The Preferences windows for its Address Book and iCal applications present simpler options to download Google Calendar schedules and synchronize your contacts list with one hosted at Google -- though the latter option suffers from Google's apparent inability to deal with middle names. The WiFi icon at the top right of the screen finally shows the signal strengths of nearby networks.

One of Snow Leopard's most welcome tweaks is even harder to spot: its belated cleanup of the Services menu, which lets you execute simple actions on selected text or files. This formerly cluttered, uneditable list now shows only the tools relevant to the item you've selected and allows you to edit its contents.

More than most earlier OS X upgrades, Snow Leopard may not accept all of your existing software and hardware. Some of these compatibility issues are easily fixed; although it doesn't install the Rosetta software needed to run applications written for Apple's old PowerPC chips, it will download and set up that component for you when you try to start up a PowerPC program. Others have no simple cure.